This application is based on and incorporates herein by reference Japanese Patent Application No. 2001-20835 filed on Jan. 29, 2001.
1. Field of the Invention
The present invention relates to a wiper apparatus for wiping a windshield or the like of a vehicle.
2. Description of Related Art
Besides a conventional wiper apparatus having a wiper arm that swings about a single stationary axis to wipe a windshield or the like of a vehicle with a wiper blade attached to a distal end of the wiper arm, there has been proposed a wiper apparatus that uses a four-bar linkage mechanism to provide a wider wiping range on the windshield, as shown in FIG. 8. Such a wiper apparatus includes first to third levers 51-53. A base end portion of the first lever 51 is secured to an upper end portion of a first support shaft 54 that is rotatably supported by a vehicle body (not shown). A base end portion of the second lever 52 is secured to an upper end portion of a second support shaft 55 that is rotatably supported by the vehicle body (not shown). The third lever 53 constitutes an arm head of a wiper arm. A base end portion of the third lever 53 is rotatably connected to a first connection 51a arranged at a distal end portion of the first lever 51. A middle portion of the third lever 53 is rotatably connected to a second connection 52a that is arranged at a distal end portion of the second lever 52 and is spaced away from the first connection 51a by a predetermined distance.
The wiper blade (not shown) for wiping the windshield is connected to a distal end portion of the third lever 53 through a retainer (not shown) of the wiper arm.
A swing lever 56 is connected to a lower end portion of the first support shaft 54. The swing lever 56 reciprocally swings within a predetermined angular range when it is driven by a driving force of a motor 60 transmitted through a rod 57.
In this wiper apparatus having the four-bar linkage mechanism, when the first lever 51 swings together with the swing lever 56 due to the driving force of the motor 60, the second and third levers 52, 53 also swing while keeping the predetermined space between the first connection 51a and the second connection 52a. During this operation, the base end portion (the first connection 51a) of the third lever 53 reciprocally swings about the first support shaft 54 along an arcuate path. Also, the entire third lever 53 swings about the first connection 51a in a direction different from a direction of the reciprocal movement of the base end portion of the third lever 53. With reference to FIG. 8, while the wiper apparatus is stopped or rested, a distance between the first support shaft 54 and the second connection 52a becomes a length xe2x80x9cCxe2x80x9d. On the other hand, during the wiping operation of the wiper apparatus, the distance between the first support shaft 54 and the second connection 52a becomes equal to a sum of a length xe2x80x9caxe2x80x9d and a length xe2x80x9cbxe2x80x9d (here, the length xe2x80x9caxe2x80x9d is the length between the first connection 51a and the second connection 52a, and the length xe2x80x9cbxe2x80x9d is the length between the first support shaft 54 and the first connection 51a). As a result, the wiping range of the wiper blade of the above wiper apparatus is increased in comparison to the conventional wiper apparatus that has the wiper arm that swings about the single stationary axis.
The above-described wiper apparatus having the four-bar linkage mechanism is generally arranged at a lower end side of the windshield. More specifically, a cowl louver is arranged at the lower end side of the windshield, and middle portions of the first and second support shafts 54, 55 are received in through holes 58, 59 (each depicted with a dot-dot-dash line in FIG. 8) of the cowl louver, respectively. That is, the swing lever 56, the rod 57 and the motor 60 are arranged below the cowl louver.
On the other hand, the first to third levers 51-53 (four-bar linkage mechanism) are disposed above (outside) of the cowl louver, so that a cover for protecting the first to third levers 51-53 (four-bar linkage mechanism) from snow, twigs or other obstacles needs to be provided. This will generally result in an increase in the number of the components and hence an increase in a manufacturing cost of the wiper apparatus. Furthermore, since the first to third levers 51-53 are disposed outside of the cowl louver, an appearance of the vehicle having them is disadvantageously deteriorated.
To address this disadvantage, in place of the above wiper apparatus that uses the third lever 53 as the arm head of the wiper arm, it is conceivable to provide a wiper apparatus that has an arm support shaft projected upwardly from the base end of the third lever 53 (the first connection 51a). In this wiper apparatus, an arm head of a wiper arm is secured to the arm support shaft, and the components located below the arm support shaft are placed below the cowl louver. In this way, the four-bar linkage mechanism is not disposed above (outside) the cowl louver, so that there is no need to provide the cover or the like to protect the four-bar linkage mechanism. However, in this case, the arm support shaft supported at the first connection 51a reciprocally moves along a simple arcuate path about the first support shaft 54, and this simple arcuate path has a relatively large extent in a fore-aft direction of the vehicle. Thus, a corresponding simple arcuate through hole, which corresponds to the simple arcuate path of the arm support shaft, needs to be formed in the cowl louver in order to receive the arm support shaft and also in order to allow the movement of the arm support shaft therethrough. Such an arcuate through hole, which has the relatively large extent in the fore-aft direction of the vehicle, imposes various limitations in designing the structure for achieving the predetermined wiping range, a size of the four-bar linkage mechanism, and an accommodating space for accommodating the four-bar linkage mechanism. Thus, layout of the vehicle components is undesirably limited. Particularly, when it is desired to position the first support shaft 54 adjacent to the windshield, the arcuate through hole needs to be extended to the windshield. Because of this, it is not possible to position the first support shaft 54 adjacent to the windshield.
The present invention addresses the above disadvantages. Thus, it is an objective of the present invention to provide a wiper apparatus of a vehicle capable of achieving a wide wiping range, an improved vehicle appearance, easy component layout and elimination of a dedicated cover for protecting components of the wiper apparatus from snow, twigs or any other undesirable obstacles.
To achieve the objective of the present invention, there is provided a wiper apparatus for wiping a wiping surface of a vehicle. The wiper apparatus includes a drive source, a first swing element, a second swing element, a connecting swing element, a wiper arm and a wiper blade. The first swing element is rotatably supported by a first support element that is connected to a vehicle body of the vehicle. The first swing element has a first connection spaced away from the first support element. The first swing element is reciprocally swung about the first support element by a driving force transmitted from the drive source. The second swing element is rotatably supported by a second support element that is connected to the vehicle body and is spaced away from the first support element. The second swing element has a second connection spaced away from the second support element. The connecting swing element is rotatably connected to the first connection of the first swing element and is also rotatably connected to the second connection of the second swing element in such a manner that the first connection is spaced away from the second connection. The connecting swing element has an arm support shaft that is arranged at an offset position offset from a line connecting between the first connection and the second connection. The wiper arm is secured to the arm support shaft of the connecting swing element to integrally move therewith. The wiper blade is connected to a distal end of the wiper arm to wipe the wiping surface of the vehicle.
To achieve the objective of the present invention, there may be alternatively provided a wiper apparatus for wiping a wiping surface of a vehicle. The wiper apparatus includes a drive source, a first swing element, a second swing element, a connecting swing element, a first wiper arm, a first wiper blade, a second wiper arm and a second wiper blade. The first swing element is rotatably supported by a first support element that is connected to a vehicle body of the vehicle. The first swing element has a first connection spaced away from the first support element. The first swing element is reciprocally swung about the first support element by a driving force transmitted from the drive source. The second swing element is rotatably supported by a second support element that is connected to the vehicle body and is spaced away from the first support element. The second swing element has a second connection spaced away from the second support element. The connecting swing element is rotatably connected to the first connection of the first swing element and is also rotatably connected to the second connection of the second swing element in such a manner that the first connection is spaced away from the second connection. The connecting swing element has an arm support shaft that is arranged at an offset position offset in a direction away from the wiping surface of the vehicle from a line connecting between the first connection and the second connection. The first wiper arm is secured to the arm support shaft of the connecting swing element to integrally move therewith. The first wiper blade is connected to a distal end of the first wiper arm to wipe the wiping surface of the vehicle. The second wiper arm is rotatably supported at a stationary support point that is spaced away from both the first support element and the second support element. The second wiper arm swings about the stationary support point synchronously with the first wiper arm. The second wiper blade is connected to a distal end of the second wiper arm to wipe the wiping surface of the vehicle. A portion of the second wiper blade is aligned with the arm support shaft in a fore-aft direction of the vehicle between the arm support shaft and the wiping surface while the second wiper blade is positioned at its rest position.